Стр.54-55 Unit 3-4 ГДЗ Комарова Ларионова 11 класс
Learn about chemistry A Read the introduction below. Then look at your clothes. What fabrics and substances are you wearing? Are any of your clothes special’, e.g.
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Приведем выдержку из задания из учебника Комарова, Ларионова 11 класс, Русское слово:
Learn about chemistry
A Read the introduction below. Then look at your clothes. What fabrics and substances are you wearing? Are any of your clothes special’, e.g. waterproof, quick dry or no-wrinkle?
acrylic
canvas
cotton
glass
leather
nylon
plastic
polyester
rubber
silicon
silk
viscose
wool
Science and technology have entered our lives in ways we dontaskt even realize. Simple chemistry is one element of science that has changed our lives. Take clothes, for example, and look at how chemistry has changed our choices.
Once, clothes were only made of natural fibres like cotton, silk or wool. Then, thanks to organic chemistry, we discovered synthetic or artificial fibres like nylon, polyester, acrylic and viscose. What are you wearing? Arc your clothes made of natural fibres, or synthetic, man-made fibres? Theytaskre probably a mixture of both.
Now think about the kind of clothes you can get that make life more convenient. There are clothes that do not need ironing, which you cantaskt stain and that keep you dry from the outside and dry from the inside. This is all chemistry. But how does it work?
B Now read about different fabrics. How could no-iron, no-stain, no-clean clothes help the environment?
No-wrinkle clothes
Cotton is a cellulose based substance. It comes from plants. In cotton, the cellulose is cross linked with hydrogen bonds which hold the fabric flat. When it gets wet or sweaty, however, the hydrogen bonds break and it starts to wrinkle. Thattasks why cotton clothes get wrinkled in the washing machine.
Ruth Kogan Benerito discovered that adding a chemical like formaldehyde would stop cotton wrinkling because it slopped the cotton getting really well formaldehyde isntaskt a very nice chemical. Ittasks toxic, yellow and stinks. I he clothes didntaskt last long and they werentaskt very healthy to wear.
A lot of research followed, and by 1992 (not that long ago) dimethylol dihydroxy ethylene urea (DMDHEU) entered the scene. It was not expensive, it didntaskt turn yellow and it wasntaskt toxic. If your clothes are wrinkle free they probably contain this chemical.
Stain-free clothes
A stain resisting substance was first discovered by Patsy Sherman in the 1950s. While Patsy was working on a latex rubber compound for tubes, she spilt a little of the substance on her canvas shoes. After some time she noticed that where the latex compound had dropped on her shoe, the shoe stayed clean. Oil and water and the stains they carried, just rolled off.
This is how Scotchgard was invented. It is the most well known way to keep clothes stain free. Now ittasks used on furniture because it doesntaskt feel very nice, but Nano Tex has created fibres that still feel soft and natural, but which are strong and wearing, dontaskt crease and stains just fall off them.
First, fabric is soaked in a solution which contains billions of tiny particles. The fabric is then heated, and these tiny particles bond or stick to the fibre. The particles actually wrap themselves around the fibre with microscopic whiskers sticking out. The whiskers trap air and are like an invisible protection on the fibre so that stains dontaskt get in. This has been used very successfully on clothes like silk ties.
Waterproofing
Researchers at the University of Zurich are working on a fabric made of polyester coated in silicon nanofilaments. This could be the most waterproof clothing ever - clothes that literally never get wet. The silicon is sprayed over the material like a gas. You cantaskt see or feel the silicon, but ittasks there and it makes the fabric hydrophobic, and the droplets of water just balance on top, but never soak into the material.
This could be a revolutionary new material for swimming costumes. It is possible that this is also the first step towards self cleaning clothes, or clothes that control smell. Ittasks probably extremely expensive so people wontaskt stop using waterproof clothing, such as Gore Tex, yet.
C Answer the questions.
1 Why does cotton wrinkle when it gets wet or sweaty?
2 Why is formaldehyde unpleasant? Can you think of any other use of formaldehyde?
3 Was the discovery of Scotchgard an accident? Why?
4 Why is the Nano-Tex product better than Scotchgard for clothes?
5 Imagine the way that silicon is put on the polyester fabric. Why do you think they put it on like this?
6 Write a definition for hydrophobic.
7 Can you think of a benefit of a swimming costume that doesntaskt get wet?
Unfired state exam
Steps to success
In Speaking Task 1 look at the words in the text before you read them aloud and try to imagine how they sound. For longer words, try to find the different parts of the word.
The stress is usually on the main part. For phrases, stress the key words.
D Choose a paragraph from the text and read it aloud.
Imagine that you are preparing a project with your friend. You have found some interesting material for the presentation and want to read it to your friend. You have 1.5 minutes to read the text silently, then be ready to read it aloud. You will not have more than 1.5 minutes to read it.
Project: Research nanotechnology
Go onto the Internet and find out what nanotechnology is. Find three uses that nanotechnology can be applied to.